SUMMARY(#br)Feed‐in tariff (FIT) has been enforced in order to promote the utilization of renewable energy since 2012 in Japan. In consideration of FIT, we propose an integration plan for incinerator plants (IPs) with highly efficient power generation for the whole area of a prefecture. The plan includes disposal of forest biomass using the reserve capacity of IPs. The model prefecture's population is set to 1,200,000 and the proportion of the forested area is set to 70% of the model area based on data for northeastern Japan. The present 16 IPs are integrated into three new IPs. A relay transportation (RT) facility for waste is located at a decommissioned IP, and the waste from the area is transported to the new IP. In order to calculate the RT costs, an approximation formula for the RT... distance is estimated via the IPs integration study. The plan will realize about 37% cost reduction and 1.8‐fold CO2 reduction including RT as compared to the plan to update the current IP situation. Forest biomass of 56,500 tons per year, which is about 43% of available forest biomass volume in the model prefecture, can be disposed of at new IPs. On the other hand, enough profit is not expected from the dedicated biomass power generation plant as a result of wood chip processing fees. The plan will help to develop local forestry.